Spindle repair

Working for you for almost 20 years

With our worldwide on-site spindle consulting services, we have been an indispensable partner for failure analysis and the repair of grinding, milling and rotary spindles since the year 2000. We guarantee the fast, flexible and reliable repair, optimization and modification of motor spindles and externally driven spindles of all types and brands. This ensures optimum downtime and cost savings.
Our outstanding success with large automotive suppliers proves our high level of expertise in all areas of spindle repair. In addition, we have the entire spindle “environment” in view because that is precisely where the problems – and thus the potential for savings – often lie.
Our spindle repairs and the individual spindle service go beyond simple repair: thanks to precise optimization, we make your motor or belt spindle as efficient and powerful as a new one.
– Markus Kern, CEO
KERN GmbH Spindle Full-Service

A success concept – our service process

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On request: individual telephone consultation

Ask us your question about anything “spindle”! We give you tailor-made advice about your problem, free of charge, and look for an optimal solution. We are happy to give you valuable tips on preventive maintenance – and on other topics as well.

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Spindeleingang in der KERN Niederlassung

If you need repair or analysis, send your spindle to us. On request we organize the dismantling and transport for you.

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Detailed failure analysis

  • Dismantling
  • Leak testing
  • IKZ testing
  • Free testing of all electronic and mechanical components
  • Innovative failure report with complete photo documentation for you

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Preparation of the quote, approval of the customer

Based on our failure analysis, we create and send you a detailed estimate.

Only after acceptance and release do we start with the spindle repair.

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Spindle preparation

  • Cleaning using new, innovative cleaning technology with 1 µ filter technology
  • Chromium-plating/grinding of the bearing seats
  • Production of parts
  • Preparation of HSK/SK

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Spindle repair/optimization

We implement your spindle and optimize it:

  • Vibration reduction of the rotating components
  • Adjustment of the electrical and mechanical components
  • Technical optimization if necessary

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Test field and inspection

We test your spindle using the most modern test technology:

  • Mobile precision balancing of the spindle
  • Another leakage test
  • Testing of electrical and mechanical components
  • Individual test protocols (BCU-bearing values, vibration values, etc.)
  • Professional Dispatch

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Long-term advice

When your repaired spindle is successfully put into operation, that is just the beginning of the service provided by KERN: We advise you in the long term, give you technical support and are at your disposal for further inquiries and detailed information at any time.

We look forward to your call/inquiry

We repair roller bearing spindles from ALL manufacturers

Here is a small selection

Holistic repair, optimization and conversion of rolling spindles

For a perfect match

The primary goal for each of our customer orders is to maximize the service life of the motor spindle or the externally driven spindle in the machine. For this purpose, we use various repair, optimization and modification measures to ensure that the spindle is not only repaired, but that it is also optimally adapted to your specific operating conditions in the machine: there is often not a smooth interplay between the spindle and the machine, and this gives rise to recurring spindle failures.

Innovative failure analyses for individual solutions

To find the best solution for your motor spindle or externally driven spindle, we analyze the exact causes of failure using the latest technology on our factory premises. Due to our neutral position as an independent spindle repair service, we can make objective failure reports for our customers. After dismantling and analyzing your spindle using one of the most advanced failure analysis methods, we will inform you in a detailed breakdown report about all causes and improvement measures necessary on the spindle and the machine.
Depending on individual requirements, damaged parts of the spindle are replaced by new ones, components are carefully optimized (by means of an upgrade) or functionalities are completely modified (redesigned) to achieve the maximum power potential of the spindle.

Optimizations for maximum performance

We are thus able to make the spindle not only better than new by means of optimizations, but at the same time more efficient and cost-effective compared to new or replacement spindles. Optimal adjustment to the machine ensures increased downtime and thus sustainable efficiency.
With this strategy, you will benefit from more effective production facilities and sustainable cost savings.

What our customers say

Thank you again for the quick repair, very good customer service and cooperation in the repair of our STEPTEC spindle. The service technician who came out to our site yesterday and installed the spindle – he said he had never had a repaired spindle from STEPTEC that was so good! In terms of concentricity, etc. I also look forward to continuing the great cooperation with you in the future!”
-Maik Widowski
KIEFER Werkzeugbau GmbH

I will be happy to take your request directly!


Aerospace industry, Germany
Aircraft Philipp: 50% reduction of spindle failure rate within 2 years
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  • Spindle repair
  • Spindle repair
  • Spindle repair
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  • Spindle repair
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Automotive manufacturing and suppliers (automotive parts) , Germany
Bosch/Weiss motor spindle repair
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    Wood processing,
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      Electronic industry/plant engineering,
      GMN Spindle repair for Fritz Studer AG
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        Automotive manufacturing and suppliers (automotive parts) , Germany
        Hüller Hille spindle repair for ZF
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        Agriculture, Aerospace industry, Germany
        Kessler spindle repair for Liebherr: 30% savings compared to a new spindle
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          Automotive manufacturing and suppliers (automotive parts) , Germany
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            Automotive manufacturing and suppliers (automotive parts) , Germany
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              Automotive manufacturing and suppliers (automotive parts) , Germany
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                With suitable conversion and re-engineering measures, we ensure reliable machine availability and bring your productivity to the next level – while reducing maintenance costs.

                Services for all spindle manufacturers, types and brands

                Regardless of the spindle type, make, manufacturer or reason for failure: we achieve the maximum performance potential for the complete range of motor or belt spindles of our customers.

                • Grinding spindle
                • Milling spindle
                • Compressed air spindle
                • Lathe spindle
                • Special spindle
                • Dressing spindle
                • Slot spindle
                • Work piece spindle
                • Tool change spindle
                • Franz Kessler
                • Weiss
                • GMN
                • Chiron
                • Step-Tec
                • Fischer
                • Gamfior
                • Voumard
                • UVA
                • Omlat
                • Makino
                • Precise
                • uvm.

                Milling machines

                • DMG, Deckel Maho
                • Chiron
                • SW
                • Heller
                • Grob
                • Weisser
                • Mikron
                • Hurco
                • Stama
                • MAG
                • Haas
                • uvm.

                Grinding machines

                • Bahmüller
                • Juncker
                • Studer
                • Buderus
                • Mikrosa
                • Ewag
                • Bridgeport
                • Präwema
                • uvm.

                Lathe machines

                • Gildemeister
                • Mazak
                • Emco
                • Okuma
                • Tornos
                • TOS
                • Nakamura
                • Traub
                • uvm.
                • Bearing damage
                • Strong temperature development (overheating)
                • Rotating union defect
                • Water damage
                • Winding end
                • Measurement system error
                • Tensioner problems
                • Insufficient clamping force
                • Spindle crash
                • Measurement system error
                • Winding damage
                • Strong vibrations/noises
                • Sealing air
                • Exterior/interior cooling defect
                • Hydraulic system defect
                • Air system defect
                • Engine cooling defect
                • Cone damaged
                • Release unit damaged
                • Clamping system damaged
                • Interface wear
                • Encoder errors
                • Oil and coolant leakage
                • And many more

                How does a spindle repair work at KERN?

                1. Receipt of spindle

                Once we have received your motor or belt spindle, first an extensive check is carried out, both visually and exhaustively. If we have already repaired the spindle type before, we can rely on our extensive experience and know-how assets.

                2. Detailed failure analysis

                In order to analyze the cause of failure in detail, the spindle is thoroughly tested before it is dismantled. This includes a leak test, IKZ testing, a test of all electronic and mechanical components such as clamping system, clamping force, encoder, sensors, test of the stator, concentricity and run, as well as testing of the rotating union, etc. During dismantling, each step is carefully documented. You will receive our detailed breakdown report with complete photo documentation.

                3. Preparation of an estimate and release by the customer

                Based on the detailed failure analysis, a cost estimate is prepared and discussed with you. We explain the reasons for the failure and why we want to make possible optimizations on your spindle. Once we receive your release, we will immediately start assembling your spindle.

                4. Spindle preparation

                Each item is cleaned with our new innovative cleaning machine with built-in 1 µ filter technology. All damaged and worn-out items are sent to our suppliers for processing and complete overhaul. The clamping system is completely analyzed and completely replaced according to the damage findings or brought back to new condition by means of a complete overhaul. The release cylinder is completely overhauled by the original manufacturer. The bearing seats are chromium-plated and ground. Depending on the results of the damage, individual parts such as the HSK mount are completely redone. The HSK/SK mount is prepared as well as the planned installation if necessary. The stator receives a new winding. The rotary feedthrough is also analyzed by one of our industry experts and repaired if necessary.

                5. Spindle repair and optimization

                When the spindle is mounted, all the necessary components such as intermediate rings, the HSK flange, the bearing cover, etc., are adjusted to achieve the optimum bearing preload. The oscillation of all rotating components is reduced by balancing, like the spindle shaft, with a balancing quality of G 1.0. Then all electrical and mechanical components are adjusted and tuned, such as the encoder, all sensor systems, plug installation, concentricity/axial run-out, stator (KTY, PTC), etc. The spindle is technically optimized and modified depending on the application. The cooling circuit as well as all hydraulic components are sealed and tested.

                6. Test run and final test

                We test your spindle using the latest testing technology. The spindle is balanced on our test stand with a special mobile balancing device. Depending on the spindle type and speed, we carry out an extensive vibration analysis procedure and achieve vibration values of significantly below 0.5 mm/s. Each spindle is tested for at least one complete working day. Temperature, bearing characteristics, as well as vibration values, etc., are monitored. After this, a new leak test is carried out, as well as a test of all electrical and mechanical components. When your spindle is sent back to you, you will receive an individual test protocol in which you can find all the testing data, including encoder protocol, BCU bearing values, vibration values and some other data.

                Further details on spindle repair with KERN Spindle Full-Service

                Our network of exclusive partners in highly specialized fields of competence is the prerequisite for the high quality of our work, which makes each spindle new and often even better than before.

                These industry experts take over the production of new and individual spare parts for assembly in the spindle or restore the precise functionality of components.

                We are technological pioneers in the field of spindle repair and offer you only the latest technology. One example of this is our new cleaning machine, which ensures perfect cleaning results – sustainable, emission-free, efficient, fast and thorough. And with our modern Siemens test stand, we are ideally positioned for all motor parameters and can therefore test each spindle individually.

                Our range of services includes additional services: balancing technology (in accordance with DIN ISO 1940), grinding technology, measurement and testing technology. We have a complete machine park with the means to completely grind tool cones.

                We dismantle and analyze the spindle and inform you with the condition and failure report about causes and possible improvement measures on the machine; at the same time, we provide you with a detailed cost estimate.

                With the repair of main spindles and tool change spindles of all turning and milling machining centres (manufacturer-independent), our spindle full service is complete. Neither the spindle design nor the type of bearing plays any role in this case.

                Our spindle service offer


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